In recent years, electronic devices such as mobile phones and PCs have been increasing in functionality and versatility, and decreasing in size. More and more such electronic devices have been using an opening mechanism which enables them to be opened or closed by rotating or sliding a movable case with respect to a solid case. With this trend, opening mechanisms used for these electronic devices also have been expected to have a thinner profile and to be less expensive.
One such conventional opening mechanism and an electronic device using it will be described as follows with reference to FIGS. 4A-4B and 5. Note that FIGS. 4A and 4B are not limited to the conventional mobile phones, but hold true to general mobile phones. FIG. 5 is an exploded perspective view of the conventional opening mechanism. Solid body 1 made of metal such as steel material is provided on its top surface with movable body 2 made of metal. Solid body 1 is also provided on its both side surfaces with guide grooves 1A as a guide mechanism, whereas movable body 2 is provided on its inner side surfaces with projections 2A. Projections 2A are inserted into guide grooves 1A to hold movable body 2 in such a manner as to be slidable in the back-and-forth direction with respect to solid body 1.
Spring 3, which is made of steel wire or the like and coiled a plurality of times at its center, is inserted at one end into hole 1B of solid body 1 and at the other end into hole 2B of movable body 2.
Disposing spring 3 that is in a little sagged state between solid body 1 and movable body 2 energizes movable body 2 in the forward direction, that is, in the direction opposite to the arrow shown in FIG. 4B with respect to solid body 1, thereby forming opening mechanism 5.
Opening mechanism 5 thus structured is attached as shown in the perspective views of the mobile phone in FIGS. 4A and 4B. More specifically, solid body 1 is fixedly attached to solid case 6, which is provided on its top surface with operation unit 6A consisting of a plurality of keys. Movable body 2 is fixedly attached to movable case 7, which is provided on its top surface with display unit 7A such as a liquid crystal display element, voice output unit 7B such as a speaker, and voice input unit 7C such as a microphone. Opening mechanism 5 makes movable case 7 held in such a manner as to be slidable in the back-and-forth direction with respect to solid case 6, thereby forming an electronic device.
In the aforementioned structure, while movable body 2 is being energized in the forward direction with respect to solid body 1 by spring 3, movable case 7 to which movable body 2 has been attached is closed with respect to solid case 6 as shown in FIG. 4A.
Sliding movable case 7 that is in the closed state by hand in the backward direction indicated by the arrow of FIG. 4B allows movable body 2 attached on movable case 7 to be slid in the backward direction. When hole 2B of movable body 2 exceeds the position of hole 1B of solid body 1, spring 3 is reversed to energize movable body 2 in the backward direction so as to open movable case 7, thereby allowing the operation of operation unit 6A thus exposed.
In this manner, movable case 7 can be closed or opened with respect to solid case 6 by sliding movable body 2 attached to movable case 7 in the forward or backward direction, thereby making spring 3 energize movable body 2 in the forward or backward direction.
Japanese Patent Unexamined Publication No. 2003-110675 discloses a mobile phone having this structure.
However, the aforementioned conventional opening mechanism and electronic device using this mechanism has a guide mechanism structured as follows. Solid body 1 made of metal is provided on its both side surfaces with guide grooves 1A as shown in FIG. 5, and movable body 2 is provided on its inner side surfaces with projections 2A which are inserted into guide grooves 1A. As a result, movable body 2 is slidable in the back-and-forth direction with respect to solid body 1. This structure requires that solid body 1 have a certain degree of thickness, making it impossible for the opening mechanism to have a thinner profile. Furthermore, forming guide grooves 1A on the side surfaces of solid body 1 made of metal requires a time-consuming process such as metal cutting or extrusion for component production, thereby leading to a cost increase.